NEMERTEANS 137 



follows a long series of similar rings separated from each other by an 

 average distance of a little less than the diameter of body in moderate 

 extension. Of course the separation of the rings depends largely on 

 the state of contraction of body, for when strongly contracted they are 

 less than a quarter as far apart as when extended. Nearly all the rings 

 are complete, but many are thinner ventrally than above. Some are 

 extremely fine, and others consist of double lines separated by a very 

 thin line of the red color of body. 



The general color of body becomes gradually lighter in intestinal 

 region, which often has a slightly yellowish tinge. Ventral surface is 

 of a lighter shade than dorsal, and has a grayish tinge. 



After preservation in formalin or in alcohol the body assumes a dull 

 reddish brown or purplish color, with very faint white rings. An 

 abrupt change in color usually occurs at the second white ring, the parts 

 anteriorly commonly being brownish, while those immediately behind 

 the ring are often deep purple. The white terminal border on the 

 head remains conspicuous when the worm is not strongly contracted. 



Size. Largest specimen observed was about 30 cm. long and 4 

 mm. in width, although others were less than half this size. 



In internal anatomy the species presents few deviations from that 

 described for related species of the genus. 



Proboscis of rather large size for genus, with muscular layers and 

 pair of large nerves as in other species. 



Musculature. Fibrous crossings between the external and internal 

 muscular layers of the body walls are but little developed. 



Cephalic glands are voluminous, and occupy a great portion of the 

 tissues of the head in front of the brain. 



Alimentary canal presents no striking peculiarities. 



Blood System. Cephalic blood lacunas of large size. Their 

 branches pass posteriorly as large lateral vessels, or lacunas, which 

 send off unusually numerous branches about the esophagus. These 

 esophageal lacunas pass ventrally well beneath the esophagus, and ex- 

 hibit abundant anastomoses as in some species of Cerebratulus^ The 

 rhynchoccel vessels originate some distance behind the mouth region, 

 though not as far posteriorly as in C. cingulata (p. 141). As in the 

 latter species, these vessels are short and of much less extent than in 

 many related forms. 



Nephridia. The excretory tubules are limited to about the third 

 and fourth fifths of the esophageal region. Anteriorly there are several 

 canals which branch profusely among the lateral and esophageal blood 



1 Notably C. lacteus ; Coe, Trans. Connecticut Acad. Sci., ix, p. 493, 1895. 



